As a braking apparatus for blind of such a type, there is known one disclosed in Jpn. UM Appln. Publication No. 1-45353 or Jpn. Pat. Appln. Laid-Open Publication No. 11-270257.
A braking apparatus of Jpn. UM Appln. Publication No. 1-45353 has a brake shoe drum, brake shoes frictionally engaged with the brake shoe drum by centrifugal force, and a planetary gear drive rotatably supporting the brake shoes. The planetary gear drive supports the brake shoes by a support integrally formed with a central gear thereof. Because of the function of the planetary gear drive, the support formed integrally with the central gear of the planetary gear drive rotates with an increased speed. The rotation of the support exerts centrifugal force on the brake shoes, allowing the brake shoes to be engaged with the brake drum, whereby braking power is obtained.
The support is constituted by a support piece and a pair of shafts extending from the support piece. The brake shoes are pivotally supported by the shafts, respectively.
In a fluid brake disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 11-270257, a partitioned chamber housing a liquid and an impeller and the impeller relatively rotates to cause the liquid to rotate, allowing the rotation of a winding element to which the impeller or partitioned chamber is connected to be delayed.
The impeller has a plurality of vanes. A rounded bead formed on the bottom of the vanes is slidingly inserted into a longitudinally-extending, rounded groove formed around an impeller hub.